Revert "[ci] Fix python2.7 installation error (flutter-tizen#795)"

This reverts commit b38874d.

Author: JSUYA

.github/workflows/build.yml

@@ -28,8 +28,6 @@ jobs:
       - name: Install Tizen Studio
         if: ${{ env.HAS_CHANGED_PACKAGES == 'true' }}
         run: |
-          sudo add-apt-repository ppa:deadsnakes/ppa
-          sudo apt update
           sudo apt install -y libncurses5 python3.8 libpython3.8  gettext \
             libkf5itemmodels5 libkf5kiowidgets5 libkchart2 dbus-x11 gnome-keyring
           curl https://download.tizen.org/sdk/Installer/tizen-studio_6.0/web-cli_Tizen_Studio_6.0_ubuntu-64.bin -o install.bin